1. Field of the Invention
The present invention generally relates to removable recording media and file control methods therefor, and more particularly, to a removable recording medium and a file control method that can achieve copyright protection.
2. Background Information
In a typical processing unit, such as a personal computer (PC), provided with a large-capacity storage device, such as a hard disk (HDD), processing results are written into the storage device, and data is read from the storage device and is processed when necessary. In this case, if an HDD 1 is fixed in a personal computer (PC) 2, as shown in FIG. 13, another PC cannot read and use data stored in the HDD 1, and thus, there is no copyright protection problems.
However, if an HDD is replaceable and portable (removable), as shown in FIG. 14, information on a removable HDD 4 recorded by a PC (PCA) 3 owned by user A can be read by another PC (PCB) 5 owned by user B, thereby causing copyright protection problems. For example, if the removable HDD 4 storing a file therein which is accessible only to the PCA 3 is installed in the PCB 5, the user B can read the file by using the PCB 5, thereby causing copyright protection problems.
Accordingly, the following measures are taken. An authentication number PC ID (PCA) of the PCA 3 and an authentication number HDD-ID (RM-HDD) of the removable HDD 4 that can be used by the PCA 3 are recorded, as shown in FIG. 15A, in the PCA 3 as authentication data, and an authentication number HDD-ID (RM-HDD) of the removable HDD 4 and an authentication number PC ID (PCA) of the PCA 3 that can use the removable HDD 4 are recorded, as shown in FIG. 15B, in the removable HDD 4 as authentication data. Only when both the PCA 3 and the removable HDD 4 are authenticated, can the PCA 3 use the removable HDD 4. With this configuration, the PCA 3 can use the removable HDD 4, in the situation shown in FIG. 14, while the PCB 5 cannot use the removable HDD 4, and thus, there are no copyright protection problems.
By erasing all of the information recorded on the removable HDD 4 to record authentication data shown in FIGS. 15C and 15D on the PCB 5 and the removable HDD 4, the PCB 5 can use the removable HDD 4, but in this case, the PCA 3 cannot use the removable HDD 4.
According to the definition of copyright, if an authorized user owns a plurality of personal computers, he/she can use any PC to write or read data into and from a removable HDD without presenting any problem. For example, user A having two PCs (PCA, PCA′) 3a and 3a′, as shown in FIG. 16, creates 20 pieces of music by using the PCA 3a and also creates 10 other pieces of music by using the PCA′ 3a′, and records the 30 pieces of music on the single removable HDD 4. The user A then installs the removable HDD 4 into an in-vehicle audio unit (ADU) 6 to listen to the 30 pieces of music.
In the method shown in FIGS. 15A through 15D, however, since authentication between PCs and removable HDDs is based on one-to-one correspondence, both music data in the PCA 3a and music data in the PCA′ 3a′ cannot be recorded on the same removable HDD 4. That is, when authentication between the PCA 3a and the removable HDD 4 is defined, as shown in FIG. 16, only the 20 pieces of music can be written into the removable HDD 4 and the user A cannot listen to the other 10 pieces of music stored in the PCA′ 3a′. To write the 10 pieces of music stored in the PCA′ 3a′ into the removable HDD 4, the information concerning the usage of the removable HDD 4 by the PCA 3a stored in the removable HDD 4 should be completely erased, and then, the authentication data shown in FIGS. 15C and 15D are recorded on the PCA′ 3a′ and the removable HDD 4.
As described above, according to the one-to-one authentication method shown in FIGS. 15A through 15D, a user cannot write files, for example, music data, stored in a plurality of PCs into a removable HDD.
The user may also wish to write data recorded on a plurality of removable HDDs into a PC so as to process the data, for example, edit the data. According to the one-to-one authentication method shown in FIG. 15, however, data cannot be written into a single PC from a plurality of removable HDDs. For example, if authentication data shown in FIG. 17 is written into the PCA 3a, the PCA 3a cannot use a medium other than a removable HDD 4a, in other words, the PCA 3a cannot use a removable HDD 4a′. 
Accordingly, a one-to-many authentication method for enabling the use of the removable HDD 4 in a plurality of PCs can be considered. For example, (1) the ID of the PCA 3a and the ID of the removable HDD 4 that can be used by the PCA 3a are recorded, as shown in FIG. 18A, in the PCA 3a as authentication data; (2) the ID of the PCA′ 3a′ and the ID of the removable HDD 4 that can be used by the PCA′ 3a′ are recorded, as shown in FIG. 18B, in the PCA′ 3a′ as authentication data; and (3) the ID of the removable HDD 4 and the IDs of the PCA 3a and the PCA′ 3a′ that can use the removable HDD 4 are recorded, as shown in FIG. 18C, in the removable HDD 4.
With this arrangement, the removable HDD 4 can be installed into each of the PCA 3a and the PCA′ 3a′ so that the user can record data, for example, music data, created by using the PCA 3a and the PCA′ 3a′ on the removable HDD 4 and listen to the music with an audio unit. For example, the user first installs the removable HDD 4 into the PCA 3a, as shown in FIG. 19, and records the 20 pieces of music data created by the PCA 3a on the removable HDD 4. The user then installs the removable HDD 4 into the PCA′ 3a′ and records the 10 pieces of music data created by the PCA′ 3a′ on the removable HDD 4, and then installs the removable HDD 4 into the audio unit (ADU) 6. This enables the user to play back and listen to the 30 pieces of music data with the audio unit 6.
In the one-to-many authentication method shown in FIGS. 18A through 18C, when the PCA 3a is authenticated, the PCA 3a can access all files recorded on the removable HDD 4, in other words, the PCA 3a can access files created by the PCA′ 3a′. Similarly, when the PCA′ 3a′ is authenticated, the PCA′ 3a′ can access all the files recorded on the removable HDD 4, in other words, the PCA′ 3a′ can access files created by the PCA 3a. If the user of the PCA 3a and the user of the PCA′ 3′ are the same user, there is no copyright protection problem. However, if the users of the two PCs are different and if one of the users is dishonest, copyright protection problems may occur. For example, the user B of the PCA′ 3a′ may use the files recorded on the removable HDD 4, which are accessible only to the user A of the PCA 3a, without permission from the user A. Likewise, the user B may use the files recorded on the removable HDD 4 created by the user A of the PCA 3a without permission from the user A.
Another known copyright protection method is disclosed in Japanese Unexamined Patent Application Publication No. 2002-6978. When work is suspended, data in the memory of a PC is stored in an external storage device, and the stored data is reconstructed by entering a password to continue the work.
However, in the invention disclosed in the above publication, the copyright of files written into a removable HDD cannot be protected.